These are semi-permanently attached with heavy-duty velcro so they stay in place while we are on the road. They were sized so they don't interfere with bunk set-up. We like 'em. Each shelf is supported by a vertical support (along the wall) that you can't see in the picture.
The original design had one less tier. It wasn't exactly what I wanted so they ended up in the fire pit. Why not - white pine with an oil base finish?